Catalyst composition free from noble metals

ABSTRACT

A noble metal-free catalyst composition is obtainable by 
     a) preparing an aqueous mixture comprising 
     i) a salt of at least one base metal selected from among the elements having atomic numbers 21-32, 39-42, 48-51, 57-75 and 81-83; 
     ii) phosphate ions; and 
     iii) at least one nitrogen source; and 
     b) evaporating the aqueous mixture obtained and drying the catalyst composition thus formed. The catalyst composition prepared can be used for producing hydrogen peroxide and for the epoxidation of olefins.

BACKGROUND OF THE INVENTION

The present invention relates to a noble metal-free, solid catalystcomposition, its preparation, its use for producing hydrogen peroxideand its use in the epoxidation of olefins.

1. Field of the Invention

Hydrogen peroxide is nowadays widely used as a clean oxidant, forexample for the bleaching of paper and cellulose, for the removal of SO₂from waste gases, in the electronics industry in semiconductormanufacture, and for sterilization, for example deodorization ordisinfection of packing material. In organic chemistry, hydrogenperoxide is used particularly in epoxidation and hydroxylationreactions, where hydrogen peroxide can also be generated in situ.

2. Discussion of the Background

According to the prior art, hydrogen peroxide is nowadays preparedlargely by the anthraquinone process (cf. Ullmann's Encyclopedia ofIndustrial Chemistry, 5th edition, vol. A13, pp. 443 ff). The substep ofhydrogenation is here usually carried out in the presence of a metalcatalyst such as palladium black or Raney nickel. In addition,heterogeneously catalyzed preparative processes in which noble metals onvarious supports are used as catalyst have been described. Thus, in U.S.Pat. No. 5,320,821, Pd/heteropolyacid is used as catalyst to preparehydrogen peroxide from the elements. Furthermore, JP 5017106-A disclosesthe use of silica or zeolites together with platinum metals and EP 0 537836 discloses the use of zirconium oxides together with Pd.

However, these processes often require the use of halogen compounds aspromoters and stabilizers, as described, for example, in U.S. Pat. No.5,320,821.

In organic oxidation reactions, it is possible to use hydrogen peroxideformed catalytically in situ directly or in combination withperoxo-oxygen transferers (cf. G. Goor in G. Strukul, "CatalyticOxidations with Hydrogen Peroxide as Oxidant", pp. 13-43, 1992 KluwerAcademic Publishers). In particular, known heterogeneous oxidationcatalysts are titanium-containing zeolites whose preparation isdescribed, for example, in DE 3047798. Zeolites of this type are used totransfer oxygen to monoolefins and diolefins (cf. EP 0 100 119 and EP 0190 609). Compared with the industrial oxidation by the chlorohydrinprocess (cf. K. Weissermel, H.-J. Arpe, "Industrielle OrganischeChemie", 3rd edition, VCH Verlag (1998) pp. 284-289), the processaccording to EP 0 100 119 has the advantage of making, for example,propylene oxide obtainable in high selectivity from propene. In J. Chem.Soc. Chem. Commun. (1992) 1446-7), Tatsumi describes the hydroxylationof benzene and the oxidation of hexane using hydrogen/oxygen overmetallic palladium on TS-1 silicalite, but only low reaction ratescompared with hydrogen peroxide are observed.

In addition, DE-A 44 25 672 discloses improved noble metal catalystscontaining titanium zeolites and processes for preparing propylene oxidefrom hydrogen, oxygen and propene. The catalyst systems describedtherein are very satisfactory, for example, in terms of reactivity,selectivity and stability. However, they nevertheless have thedisadvantage, like other heterogeneous oxidation catalysts known fromthe prior art, of containing an expensive noble metal as catalyticallyactive constituent. This is a significant economic disadvantage,particularly for the large-scale industrial production of the oxidationproducts such as propylene oxide.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a noble metal-freeheterogeneous catalyst which is also essentially free of halogen atomsand can be employed both in the preparation of hydrogen peroxide andalso in the catalytic oxidation of organic molecules such as, inparticular, the epoxidation of olefins.

We have found that this object is achieved by a solid catalystcomposition comprising a base metal component, phosphate and a nitrogencomponent as essential constituents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an x-ray diffractogram of the product of Example 1.

FIG. 2 shows an x-ray diffractogram of the product of Example 3.

FIG. 3 shows an x-ray diffractogram of the product of ComparativeExample 1.;

Metals suitable according to the present invention are the d and felements, i.e. elements of the 4th to 6th period from the groups IIIB,IVB, VB, VIB, VIIB, IB, IIB, IIIA, IVA and VA of the Periodic Table,i.e. Sc, Ti, V, Cr, Mn, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Cd, In, Sn, Sb,La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,Hf, Ta, W, Re,Tl, Pb, Bi and additionally Fe, Co and Ni.

DETAILED DESCRIPTION OF THE INVENTION

The present invention accordingly provides a catalyst composition(hereinafter referred to as metal phosphate) which is obtainable by

a) preparing an aqueous mixture comprising

i) a salt of at least one base metal selected from among the elementshaving atomic numbers 21-32, 39-42, 48-51, 57-75 and 81-83;

ii) at least one phosphate ion and

iii) at least one nitrogen source; and

b) evaporating the aqueous solution obtained and drying the catalystcomposition thus formed, with or without gentle warming, so as to retainits catalytic activity.

The aqueous mixture of stage a) is preferably obtained by dissolving thecomponents i), ii) and iii) in an aqueous solvent such as water or anaqueous alcoholic, for instance an aqueous ethanolic, solvent. However,the preferred solvent is water. The components can be dissolved togetheror separately from one another. However, preference is given toseparately preparing two solutions, one of which contains the base metalsalt and the other contains the phosphate component, and subsequentlycombining the two solutions. The nitrogen source required can be presentin one or both of the solutions.

In the preparation of the metal phosphate catalysts of the presentinvention it is advantageous to first dissolve the metal component inthe form of readily soluble salts in aqueous solution and then to addthe phosphate in dissolved form with steady stirring.

The method of selecting the most suitable pH and temperature range forthe preparation of a particular catalyst composition is known to thoseskilled in the art. In the preparation of the component solutions or theaqueous mixture it is usually sufficient to work at from 10 to 60° C.,preferably from about 20 to 30° C. However, depending on the solutionbehavior of the components used, heating of one component solution or ofthe aqueous mixture above the value mentioned can be employed. Duringthe preparation of the component solutions or the mixture, particularmeasures for adjusting the pH are usually not necessary. However,depending on the solution behavior of individual components, theaddition of pH-adjusting substances such as customary acids or bases, orcustomary buffer substances, can be advantageous.

The aqueous mixture produced as described in stage a) preferablycomprises the base metal ions (M) such as metal cations, phosphate (P)and nitrogen source (N) in a molar ratio in the range of about1:0.8-1.4:0.6-4.0, for example 1:1:1 or 1:1:4.

The respective concentration of the individual components present in theaqueous mixture of the present invention can vary within a wide rangeand is essentially determined by the solubility of the compounds used.However, it is advantageous to prepare aqueous solutions which are asconcentrated as possible in order to keep the time and energyrequirements for the evaporation of the aqueous mixture as low aspossible, provided that the formation of the catalytically active metalphosphate of the present invention is not impaired thereby. Thus, forexample, the metal component and the phosphate component can be present,independently of one another, in a concentration in the range from about0.1 to about 1.5 mol/l, for example from about 0.25 to about 0.85 mol/l.The nitrogen source(s) can be present, for example, in a concentrationin the range from about 0.1 to about 5 mol/l, for example from about0.25 to about 3.5 M. When ammonium ions are used as nitrogen source, themetal component, phosphate and ammonium are preferably present in themixture in approximately equimolar amounts, with the concentration ofeach of the three components being able to be from about 0.25 to about0.85 mol/l.

During evaporation and drying of the aqueous mixture, the conditions arepreferably selected such that complete loss of the nitrogen componentfrom the catalyst composition is essentially avoided. In particular, theconditions should be selected so that the proportion of nitrogen in thecatalyst composition after completion of drying is reduced by not morethan about 20-90 mol %, preferably about 50-80 mol %, based on thenitrogen used.

The method of selecting the most suitable drying conditions for theparticular catalyst material is known to those skilled in the art. Asshown by the accompanying examples, it is possible, for example, fordrying of the catalyst composition at a temperature which is too high toresult in complete loss of nitrogen. This loss can be detected by meansof a distinct, characteristic change in the X-ray diffraction patternsof the solid composition, as is shown by comparison of the attachedX-ray diffractograms (FIG. 1 and FIG. 3). In particular, the finestructure in the diffractogram which is conspicuous for thecatalytically active phosphates of the present invention can no longerbe detected. However, the most significant effect of the loss ofnitrogen is a decrease in or complete loss of the catalytic activity.

The catalytically active metal phosphate of the present invention isobtained, for example, when the aqueous mixture is first evaporated todryness in a pressure range from about 10 to 1000 mbar, e.g. about 15-50mbar, at from about 10 to about 200° C., e.g. about 100-140° C., and theresidue obtained in this way is dried in air at atmospheric pressure atfrom about 30 about 200°C., preferably from about 50 to about 150° C.,in particular from about 60 to about 140° C., e.g. 120° C. The dryingtime can be from about 5 to 20 hours, for example from about 8 to 12hours.

This gives solid phases which are able to form hydrogen peroxide fromhydrogen and oxygen by heterogeneous catalysis without noble metals andhalogen-containing promoters.

In the catalyst composition thus prepared, base metal (M), phosphate (P)and nitrogen (N) can be present in a molar ratio ofM:P:N=1:0.9-1.3:0.9-1.7, for example in a ratio of 1:1-1.3:1.1-1.5 orabout 1:1.1-1.2:1.1-1.5.

For preparing the aqueous mixture as described in stage a), particularpreference is given to using water-soluble base metal salts such ashalides, e.g. fluorides, bromides or chlorides, hydroxides, nitrates,sulfates, cyanides or other water-soluble salts. The use of nitrates isparticularly preferred. Base metals used are particularly elementshaving atomic numbers 21-32, 39-42 and 48-51. The oxidation state of themetal ion can vary and be, for example, +1, +2, +3, +4, +5, +6 or +7.However, preference is given to those oxidation states of whichwater-soluble salts exist.

According to a particularly preferred embodiment, use is made of saltsof iron in the oxidation states +2, +3, +4, +5 or +6, in particular +2or +3, and salts of tin in the oxidation states +2 or +4, in particular+2.

Most preferred is the use of water-soluble iron salts such as iron(III)nitrate and water-soluble tin salts such as tin(II) chloride.

Phosphate components which can be employed according to the presentinvention are metaphosphoric and orthophosphoric acid and thewater-soluble, noble metal-free salts thereof. Particular preference isgiven to the use of water-soluble salts of orthophosphoric acid whichform phosphate, hydrogenphosphate or dihydrogenphosphate ions in aqueoussolution.

Nitrogen sources which can be employed according to the presentinvention are nitric acid and the water-soluble, noble. metal-free saltsthereof. Preferred examples which may be mentioned are water-solublenitrate salts of the abovementioned base metals. It is also possible toemploy ammonia and the water-soluble, noble metal-free salts thereof.Also usable are primary, secondary or tertiary amines or salts thereofwhich are soluble in the solvent used according to the presentinvention. Examples which may be mentioned are lower alkylamines havingup to 3 lower alkyl groups and lower alkylammonium salts having up to 4lower alkyl groups. The lower alkyl groups are preferably C₁ -C₄ -alkylgroups such as methyl, ethyl, n-propyl and n-butyl.

The preparation of the nitrogen-containing metal phosphates of thepresent invention is preferably carried out using ammonium or loweralkylammonium phosphates. Particular preference is given to usingammonium dihydrogenphosphate.

According to a specific embodiment of the present invention, iron(III)nitrate and ammonium dihydrogenphosphate give, after drying, a catalystcomposition which displays an X-ray diffractogram comprising thefollowing characteristic diffraction lines:

    ______________________________________                                                2-Theta                                                                             d                                                               ______________________________________                                                9.37  9.429                                                             18.37 4.924                                                                   28.01 3.183                                                                   28.76 3.099                                                                   35.05 2.558                                                                   37.87 2.373                                                                 ______________________________________                                    

According to a further preferred embodiment of the invention, tin(II)chloride and ammonium dihydrogenphosphate give, after drying, a catalystcomposition which displays an X-ray diffractogram comprising thefollowing characteristic diffraction lines:

    ______________________________________                                                2-Theta                                                                             d                                                               ______________________________________                                                12.79 6.915                                                             13.04 6.784                                                                   19.09 4.645                                                                   20.21 4.389                                                                   23.01 3.861                                                                   23.90 3.720                                                                   26.18 3.400                                                                   30.33 2.944                                                                 ______________________________________                                    

The 2-theta values indicated above were determined using copper K(α)radiation (wavelength 1:1.54056 Ångstrom; wavelength 2:1.54439Ångstrom). Further diffraction lines are shown in the accompanying FIGS.1 and 2.

According to a further preferred embodiment, the catalytically activemetal phosphate of the present invention is combined with an oxygentransferer as further catalytically active component. For this purpose,for example, the generally solid oxygen transferer can be suspended inthe aqueous metal salt solution prepared as described in stage a) aboveand the suspension obtained in this way can, as described above, beevaporated and dried.

While the metal phosphate of the present invention is suitable, inparticular, for use in processes for preparing hydrogen peroxide, themetal phosphate combined with the oxygen transferer is preferably usedas heterogeneous catalyst in organic oxidation reactions, for example inthe epoxidation of olefins.

The invention accordingly also provides a process for preparing hydrogenperoxide in which hydrogen and oxygen are reacted under conventionalconditions in the presence of the metal phosphate of the presentinvention and the hydrogen peroxide formed is separated from thecatalyst composition.

The invention additionally provides a process for the epoxidation ofolefins which comprises reacting the olefin catalytically in thepresence of hydrogen and oxygen. The olefin used can be any organiccompound containing at least one ethylenically unsaturated double bond.It can be aliphatic, aromatic or cycloaliphatic in nature, and it canhave a linear or branched structure. The olefin preferably contains from2 to 30 carbon atoms. More than one ethylenically unsaturated doublebond can be present, for example as in dienes or trienes. The olefin canadditionally comprise functional groups such as halogen atoms, carboxylgroups, carboxylic ester functions, hydroxyl groups, ether bridges,sulfide bridges, carbonyl functions, cyano groups, nitro groups or aminogroups.

Typical examples of such olefins are ethylene, propene, 1-butene, cis-and trans-2-butene, 1,3-butadiene, pentenes, isoprene, hexenes, octenes,nonenes, decenes, undecenes, dodecenes, cyclopentene, cyclohexene,dicyclopentadiene, methylenecyclopropane, vinylcyclohexane,vinylcyclohexene, allyl chloride, acrylic acid, methacrylic acid,crotonic acid, vinylacetic acid, allyl alcohol, alkyl acrylates, alkylmethacrylates, oleic acid, linoleic acid, linolenic acid, esters andglycerides of such unsaturated fatty acids, styrene, α-methylstyrene,divinylbenzene, indene and stilbene. Mixtures of said olefins can alsobe epoxidized by the process of the present invention.

The process of the present invention is particularly suitable for theepoxidation of propene to give propylene oxide. For this purpose, themetal phosphate of the present invention combined with the oxygentransferer is advantageously used as catalyst. While the metal phosphatecomponent catalyses the in situ production of hydrogen peroxide, theolefin is epoxidized with the aid of the transferer component.

It is here economically advantageous to allow the reaction to proceedonly in a pressure range of about 1-20 bar at about 5-70° C., inparticular at about 20-55° C. The molar ratio of H₂ :O₂ can be varied inthe range from about 1:1 to about 1:20, in particular from about 1:1 toabout 1:10.

Oxygen transferers which can be used in the catalysts of the presentinvention are, for example, titanium silicates having a pentasilstructure. As examples of silicates, particular mention may be made ofthose which are assigned X-ray crystallo-graphically to the MFI or MELstructures or MFI/MEL mixed structure. Zeolites of this type aredescribed, for example, in W. M. Meier, D. H. Olson, "Atlas of ZeoliteStructure Types", Butterworths, 2nd edition, 1987. It is also possibleto use titanium-containing zeolites having the structure of ZSM-48,ferrierite, ZSM-12 or β-zeolite. In place of the titanium, it is alsopossible for, for example, vanadium to be present in bonded form in thezeolite. Likewise, titanium-, vanadium-, molybdenum-, rhenium- ortungsten-containing mesoporous oxides as described in U.S. Pat. No.5057296 or DE-A 4407326 can also be used.

The abovementioned, particularly preferred titanium silicates having anMFI pentasil structure are prepared by crystallizing a synthesis gelcomprising water, a titanium source and silicon dioxide in anappropriate manner with addition of organic, nitrogen-containingcompounds under hydrothermal conditions, with or without the addition ofammonia solution, alkali or fluoride as mineralizer. Suitablenitrogen-containing compounds are, for example, 1,6-diaminohexane (cf.EP 0 007 081) or preferably the salts, or the free hyroxide oftetraalkylammonium salts, such as in particular tetrapropylammonium(TPA) (cf. DE-A 3047798). As described in DE-A 4138155, the use ofexpensive TPAOH can be avoided if TPABr together with ammonia are usedin its place. The latter method in particular avoids alkalicontamination of the titanium silicate; alkali contents of <100 ppm aredesirable in order to later obtain a sufficiently active epoxidationcatalyst.

The crystallization of the single-phase titanium silicate having the MFIstructure is preferably carried out at 140-190° C., particularlyadvantageously at 175° C., over a period of from about 2 to 7 days, withwell crystallized product being obtained after only about 4 days.Vigorous stirring and a high pH of about 12-14 during thecrystallization can distinctly reduce both the synthesis time and thecrystallite size.

It is advantageous to obtain, for example, primary crystallites having aparticle size of from 0.05 to 0.5 μm, but in particular less than 0.2μm.

After the crystallization, the titanium silicate can be filtered off,washed and dried at 100-1200° C. by methods known per se. To remove theamine or tetraalkylammonium compound still present in the pores, thematerial can be subjected to a further thermal treatment in air or undernitrogen. It is here advantageous to limit the temperature rise to <550°C.

The presence of the catalyst functions necessary for the olefinoxidation can be checked by IR spectroscopy; at 550 cm⁻¹ and 960 cm⁻¹there are significant bands which indicate the presence of the desiredsolid state crystallinity and also the necessary epoxidation activity.

Titanium zeolites prepared in this way can, according to a preferredembodiment, be added to the metal phosphates of the present invention.For this purpose, for example, the solution of a metal nitrate andammonium phosphate can be initially charged and the freshly calcinedtitanium zeolite can then be added in portions while stirring. Thezeolite suspension can then be evaporated at about 30-200° C., inparticular from about 50 to 100° C., under atmospheric or reducedpressure.

To modify the catalyst compositions of the present invention, themethods known from the prior art can be employed. Examples which may bementioned are shaping with the aid of a binder, ion exchange and/orimpregnation with metals, surface modification, for example by means ofCVD (Chemical Vapor Deposition) or chemical derivative formation, forinstance silylation. It is also conceivable to deposit the catalystcomposition of the present invention on a solid, inert support. Suitableinert supports are, for example, spheres, pellets or extrudates ofaluminum oxide or silicon dioxide. To prepare the supported catalystcomposition of the present invention, it is possible, for example, toadd the support particles to the abovementioned aqueous metal saltsolution prior to evaporation, if desired together with theabovedescribed oxygen transferer, and to evaporate and dry the mixtureas described above.

Depending on the organic molecule to be reacted, the catalysts of thepresent invention can be used in the liquid or gas phase or else. in thesupercritical phase. In the case of liquid phases the catalyst ispreferably used as a suspension, while in the gas-phase or supercriticalprocedure a fixed bed arrangement is advantageous.

Deactivated catalysts can be reconverted into an active form bycontrolled burning off of carbon deposits and subsequent reduction, forexample using hydrogen. In the case of a low level of deposits, thecatalyst can also be regenerated by a simple washing process. Thewashing process can be carried out as required at neutral, acid or basicpH. It may also be possible to restore the catalyst activity by means ofa hydrogen peroxide solution acidified with mineral acid.

The present invention is illustrated by the following examples.

EXAMPLE 1

Preparation of an Iron Phosphate Catalyst (catalyst A)

In a polypropylene beaker, 116 g (0.33 mol) of iron(III) nitratehexahydrate (Riedel de Haen) are dissolved at room temperature in 250 mlof deionized water and transferred to a 1 l glass flask provided withstirring. Separately therefrom, 38.3 g (0.33 mol) of ammoniumdihydrogenphosphate (NH₄ H₂ PO₄) (Merck) are dissolved at roomtemperature in 150 ml of deionized water and the phosphate solutionformed is added dropwise while stirring vigorously to the iron nitratesolution.

The solution thus formed is stirred for one further hour at roomtemperature. The reddish solution is then transferred to a rotaryevaporator and evaporated at 90° C. and 15-20 mbar. The solid obtainedis dried overnight at 120° C. in air in a convection drying oven. Theproduct displays the X-ray diffractogram shown in FIG. 1. The 2-thetavalues obtained and the associated d values and the relative intensitiesfor the diffraction lines determined are summarized in Table I below.

                  TABLE I                                                         ______________________________________                                        Peak                        Peak                                                num-    Num-                                                                  ber 2-Theta.sup.a d % ber 2-Theta.sup.a d %                                 ______________________________________                                        1    9.372    9.4287  100.00                                                                              28   38.864 2.3153                                                                              2.46                              2 10.063 8.7830 1.08 29 39.445 2.2825 2.27                                    3 14.270 6.2015 0.58 30 39.540 2.2773 2.24                                    4 16.698 5.3049 3.13 31 39.979 2.2533 2.54                                    5 17.546 5.0504 5.45 32 40.858 2.2068 1.99                                    6 18.378 4.8236 8.66 33 41.172 2.1907 4.01                                    7 18.723 4.7354 4.23 34 42.423 2.1290 2.43                                    8 21.371 4.1543 5.98 35 43.475 2.0799 1.19                                    9 22.564 3.9373 1.60 36 44.307 2.0427 1.36                                    10 22.878 3.8839 1.16 37 45.296 2.0004 2.85                                   11 23.318 3.8117 4.15 38 45.845 1.9777 1.91                                   12 25.657 3.4692 0.64 39 46.866 1.9370 2.05                                   13 26.803 3.3235 4.81 40 47.211 1.9236 2.99                                   14 28.012 3.1827 17.15 41 47.572 1.9098 3.49                                  15 28.781 3.0994 23.32 42 47.980 1.8945 3.60                                  16 29.827 2.9930 1.52 43 48.885 1.8616 1.38                                   17 30.518 2.9268 5.15 44 49.403 1.8432 3.37                                   18 31.884 2.8045 1.36 45 49.984 1.8232 1.72                                   19 33.061 2.7072 1.72 46 50.926 1.7916 2.77                                   20 33.673 2.6594 4.07 47 52.684 1.7359 0.97                                   21 34.097 2.6273 1.55 48 54.474 1.6830 1.44                                   22 34.553 2.5937 2.63 49 55.583 1.6520 1.08                                   23 35.055 2.5577 3.87 50 56.274 1.6334 2.13                                   24 35.505 2.5263 2.77 51 57.138 1.6107 2.13                                   25 36.054 2.4890 3.85 52 57.938 1.5904 3.02                                   26 37.875 2.3734 8.33 53 59.477 1.5529 3.54                                   27 38.409 2.3417 1.88 54 60.963 1.5185 1.41                                       55 61.654 1.5031 1.38                                                         56 64.950 1.4346 1.58                                                         57 66.206 1.4104 1.88                                                   ______________________________________                                         .sup.a The 2theta values indicated above were determined using copper         K(α) radiation (wavelength 1:1.54056 Angstrom; wavelength 2:1.54439     Angstrom).                                                               

The catalyst contains 22.2% by weight of iron, 14.0% by weight ofphosphorus and 8.3% by weight of nitrogen, which corresponds to a molarratio of Fe:P:N of about 1:1.13:1.5.

EXAMPLE 2

Use of the catalyst A according to the present invention for thecatalytic production of hydrogen peroxide from the elements.

A steel autoclave fitted with a glass insert (25 ml capacity) is chargedwith the catalyst from Example 1 (100 mg) in 10 ml of methanol and theautoclave is closed. In an explosion-protected facility, hydrogen is fedin at 27° C. while stirring (30 min; 10 ml/min). The pressure is thenincreased to 40 bar using nitrogen and, finally, oxygen (100 ml/min) ismetered in. After a reaction time of 4 hours, the autoclave is slowlyvented and the contents are analyzed. 0.70% by weight of hydrogenperoxide are found by means of iodometric titration. The water contentof the reaction product is 3.2% by weight.

EXAMPLE 3

Preparation of a Tin Phosphate Catalyst (catalyst B)

In a polypropylene beaker, 54.5 g (0.29 mol) of tin(II) chloride (Merck)are dissolved at room temperature in 250 ml of deionized water andtransferred to a 2 l glass flask provided with stirring. In addition,38.3 g (0.33 mol) of ammonium dihydrogenphosphate (Merck) are dissolvedat room temperature in 950 ml deionized water and the phosphate solutionis added dropwise while stirring vigorously to the tin chloridesolution. The suspension formed is stirred at room temperature for afurther period of one hour. The mixture is then transferred to a rotaryevaporator and evaporated at 90° C. and 20 mbar and subsequently washedfree of chloride using H₂ O . The solid obtained is dried overnight at120° C. in air in a convection drying oven. The product displays theX-ray diffractogram shown in FIG. 2. The 2-theta values determined andthe associated d values and the relative intensities for the diffractionlines determined are summarized in Table II below.

                  TABLE II                                                        ______________________________________                                        Peak                        Peak                                                num-    Num- 2-                                                               ber 2-Theta.sup.a d % ber Theta.sup.a d %                                   ______________________________________                                        1    11.207   7.8890  3.77  24   28.986                                                                              3.0779                                                                              20.67                              2 11.905 7.4280 4.84 25 29.578 3.0177 42.09                                   3 12.792 6.9147 85.68 26 29.838 2.9919 63.83                                  4 13.040 6.7835 84.93 27 30.335 2.9441 100.00                                 5 14.365 6.1607 26.59 28 30.867 2.8945 26.37                                  6 16.719 5.2982 5.27 29 31.742 2.8166 36.38                                   7 17.827 4.9713 4.41 30 32.180 2.7793 53.61                                   8 19.093 4.6445 23.14 31 32.850 2.7241 16.04                                  9 19.507 4.5469 14.75 32 33.347 2.6847 17.55                                  10 20.217 4.3888 20.34 33 33.797 2.6500 7.75                                  11 21.210 4.1854 13.89 34 34.033 2.6321 10.66                                 12 23.016 3.8669 50.81 35 34.861 2.5714 34.55                                 13 23.501 3.7823 19.16 36 35.228 2.5455 10.33                                 14 23.903 3.7196 44.03 37 36.115 2.4850 19.16                                 15 24.093 3.6908 38.00 38 36.541 2.4570 13.02                                 16 24.365 3.6502 8.72 39 36.754 2.4432 8.72                                   17 24.980 3.5617 16.68 40 37.464 2.3986 7.75                                  18 25.678 3.4664 16.58 41 37.744 2.3814 13.35                                 19 26.187 3.4002 57.59 42 37.898 2.3721 10.44                                 2D 26.482 3.3629 15.93 43 38.241 2.3516 32.72                                 21 27.531 3.2372 18.95 44 38.678 2.3260 26.70                                 22 28.655 3.1127 66.52 45 38.927 2.3117 10.55                                 23 28.915 3.0853 22.82 46 39.223 2.2950 15.61                               ______________________________________                                         .sup.a The 2theta values indicated above were determined using copper K(a     radiatiom (wavelength 1:1.54056 Angstrom; wavelength 2:1.54439 Angstrom).

The catalyst contains 37.0% by weight of tin, 11.2% by weight ofphosphorus and 5.1% by weight of nitrogen, which corresponds to a molarratio of Sn:P:N of about 1:1.16:1.16.

EXAMPLE 4

Use of the catalyst B according to the present invention for thecatalytic production of hydrogen peroxide from the elements.

A steel autoclave fitted with a glass insert (25 ml capacity) is chargedwith the catalyst from Example 3 (100 mg) in 10 ml of methanol and theautoclave is closed. In an explosion-protected facility, hydrogen is fedin at 27° C. while stirring (30 min; 10 ml/min). The pressure is thenincreased to 40 bar using nitrogen and, finally, oxygen (100 ml/min) ismetered in. After a reaction time of 4 hours, the autoclave is slowlyvented and the contents are analyzed. 0.38% by weight of hydrogenperoxide are found by means of iodometric titration. The water contentof the reaction product is 1.1% by weight.

EXAMPLE 5

Preparation of a titanium zeolite usable according to the presentinvention.

A four-neck flask (2 l capacity) is charged with 455 g of tetraethylorthosilicate (Merck) at room temperature and 15 g of tetraisopropylorthotitanate are added while stirring (250 rpm; blade stirrer) from adropping funnel over a period of 30 minutes. A colorless, clear mixtureis formed. Subsequently,. 800 g of a tetrapropylammonium hydroxidesolution (40% TPAOH, Alfa, diluted to 20% by weight with deionizedwater, alkali metal content <10 ppm) are subsequently added and themixture is stirred for one further hour. Subsequently, the alcoholmixture (about 460 g) formed by hydrolysis is distilled off at from 90°to 100° C. 1.5 l of deionized water are added and the now slightlyopaque sol is placed in a 2.5 l capacity stirring autoclave. The closedautoclave (anchor stirrer, 200 rpm) is heated at 3° C./min to a reactiontemperature of 175° C. After 92 hours, the reaction is ended by cooling.The cooled reaction mixture (white suspension) is centrifuged and thesolid is washed a number of times with water until neutral. The solidobtained is dried for 24 hours at 110° C. (yield 149 g). Subsequently,the template still present in the zeolite is burnt off in air by heatingat 500° C. for 5 hours (calcination loss: 14% by weight).

The pure white product has, according to wet chemical analysis, atitanium content of 1.5% by weight and a residual alkali metal content(potassium) of <0.01% by weight. The yield is 97% based on SiO₂ used.

The cristallite size is about 0.1-0.15 μm and the product shows typicalbands at 960 cm⁻¹ and 550 cm⁻¹ in the IR spectrum.

EXAMPLE 6

Preparation of an Iron Phosphate Epoxidation Catalyst According to thePresent Invention

In a polypropylene beaker, 116 g (0.33 mol) of iron(III) nitrate (Riedelde Haen) are dissolved in 250 ml of deionized water as described inExample 1. Separately therefrom, 38.3 g (0.33 mol) of ammoniumdihydrogenphosphate are dissolved in water and the phosphate solution isadded while stirring to the initially charged iron nitrate solution.

The pink solution formed is transferred to a rotary evaporator. Inaddition, a suspension of 7 g of titanium silicalite from Example 5 in50 ml of deionized water is added and the suspension is evaporated overa period of 5 hours as described in Example 1. The catalyst issubsequently dried overnight at 120° C.

The catalyst contains 10.1% by weight of iron, 6.8% by weight ofphosphorus, ?% by weight of nitrogen and 1.1% by weight of titanium.

EXAMPLE 7

Preparation of Propylene Oxide

In an explosion-protected facility, a glass pressure autoclave ischarged with 60 ml of a 50% strength aqueous methanol solution. 1 g ofthe catalyst from Example 6 is added thereto. After heating thecatalyst-containing suspension in the closed autoclave to about 40-50°C., nitrogen (30 ml/min), oxygen (30 ml/min), hydrogen (60 ml/min),propene (20 ml/min) are metered in while maintaining a constant pressureof 1 bar. After 2 hours, the off-gas stream of the reactor contains,according to gas chromatography, a C3 fraction comprising 101 ppm ofpropylene oxide as well as 17.7% by volume of propene and 0.11% byvolume of propane. These values are still observed after 6 hours.

After the end of the reaction, 260 ppm of propanediol are also detectedin the liquid reaction product.

COMPARATIVE EXAMPLE 1

Influence of the drying temperature on the catalytic activity of thecatalysts of the present invention.

Example 1 is repeated, except that the solid obtained is additionallycalcined at 550° C. in air for 5 hours.

The calcination loss is 58% by weight based on the initial weight ofmarterial. Nitrogen is no longer detected. The product now displays thedistinctly changed X-ray diffractogram shown in FIG. 3. The 2-thetavalues determined and the associated d values and the relativeintensities of the diffraction lines determined are summarized in TableIII below.

                  TABLE III                                                       ______________________________________                                        Peak                                                                            number 2-Theta.sup.a d %                                                    ______________________________________                                        1       20.400         4.3499  17.26                                            2 21.922 4.0511 2.25                                                          3 23.783 3.7382 2.19                                                          4 25.897 3.4375 100.00                                                        5 31.470 2.8404 1.42                                                          6 35.615 2.5188 9.04                                                          7 36.517 2.4586 2.25                                                          8 38.096 2.3602 17.43                                                         9 39.195 2.2965 8.87                                                          10 41.394 2.1794 10.82                                                        11 43.246 2.0903 1.54                                                         12 44.543 2.0324 2.54                                                         13 45.388 1.9965 2.19                                                         14 48.546 1.8738 14.24                                                        15 53.113 1.7229 8.33                                                         16 54.824 1.6731 1.89                                                         17 56.403 1.6300 1.65                                                         18 58.292 1.5816 9.52                                                         19 61.647 1.5033 4.73                                                         20 65.650 1.4210 14.89                                                        21 66.327 1.4081 5.44                                                       ______________________________________                                         .sup.a The 2theta values indicated above were determined using copper         K(α) radiation (wavelength 1:1.54056 Angstrom; wavelength 2:1.54439     Angstrom).                                                               

COMPARATIVE EXAMPLE 2

Use of the nitrogen-free comparative catalyst for the catalyticproduction of hydrogen peroxide from the elements.

Example 2 is repeated, but the catalyst from Comparative Example 1 (100mg) is now initially charged. After a reaction time of 4 hours, theautoclave is slowly vented and the contents are analyzed. Only 0.17% byweight of hydrogen peroxide are found by means of iodometric titration.The water content of the reaction product is 2.1% by weight.

COMPARATIVE EXAMPLE 3

Preparation of a phosphate catalyst without a metal component accordingto the present invention.

In a polypropylene beaker, 18.9 g (0.3 mol) of boric acid (Merck) aredissolved at room temperature in 250 ml of deionized water andtransferred to a 2 l glass flask provided with stirring. Separatelytherefrom, 38.3 g (0.33 mol) of ammonium dihydrogenphosphate (Merck) aredissolved at room temperature in 950 ml of deionized water and thephosphate solution is added dropwise while stirring vigorously to theboric acid solution. The suspension formed is stirred for a furtherperiod of one hour at room temperature. The mixture is then transferredto a rotary evaporator and evaporated at 90° C./20 mbar. The solidobtained is dried overnight in air at 120° C. in a convection dryingoven.

The catalyst contains 6.1% by weight of boron, 20.7% by weight ofphosphorus and 9.6% by weight of nitrogen.

COMPARATIVE EXAMPLE 4

Use of the catalyst from Comparative Example 3 for the catalyticproduction of hydrogen peroxide from the elements.

Example 2 is repeated, but the catalyst from Comparative Example 3 (100mg) is now initially charged. After a reaction time of 4 hours, theautoclave is slowly vented and the contents are analyzed. only <0.01% byweight of hydrogen peroxide are found by means of iodometric titration.The water content of the reaction product is 0.6% by weight.

We claim:
 1. A noble metal-free catalyst composition obtained by aprocess comprising:a) preparing an aqueous mixture comprisingi) a saltof at least one base metal (M) selected from the group consisting of theelements having atomic numbers 21-32, 39-42, 48-51, 57-75 and 81-83; ii)phosphate ions (P); and iii) at least one nitrogen source (N); and b)evaporating the aqueous mixture obtained and drying the catalystcomposition thus formed at a temperature of about 30 to about 200°C.wherein base metal (M), phosphate (P) and nitrogen (N) are present inthe noble metal-free catalyst composition in a molar ratio ofM:P:N=1:0.9-1.3:0.9-1.7.
 2. A catalyst composition as claimed in claim 1wherein the aqueous solution comprises metal ions (M), phosphate ions(P) and a nitrogen source (N) in a molar ratio ofM:P:N=1:0.8-1.4:0.6-4.0.
 3. A catalyst composition as claimed in claim1, wherein the base metal salt is selected from the group consisting ofwater-soluble salts of metals having atomic numbers 21-32, 39-42 and48-51.
 4. A catalyst composition as claimed in claim 1, wherein thenitrogen source is selected from the group consisting of nitric acid andthe noble metal-free, water-soluble salts thereof, amines, ammonium orlower alkylammonium salts.
 5. A catalyst composition as claimed in claim4 wherein the nitrogen source is selected from the group consisting ofwater-soluble ammonium and lower alkylammonium salts or a water-solublenitrate salt of the base metal used, and the phosphate componentcomprises dihydrogenphosphate ions.
 6. A catalyst composition as claimedin claim 1, wherein the base metal salt is selected from the groupconsisting of salts containing iron in the oxidation state +2, +3, +4,+5 and/or +6 and salts containing tin in the oxidation state +2 and/or+4.
 7. A catalyst composition as claimed in claim 1 wherein the aqueousmixture obtained from a) is evaporated at a pressure of from about 15 toabout 1000 mbar and at from about 10 to about 200° C. and the residuethus obtained is dried at from about 30 to 200° C.
 8. A catalystcomposition as claimed in claim 1 wherein the base metal componentpresent comprises iron ions and the composition displays an X-raydiffractogram comprising the following diffraction lines:

    ______________________________________                                                2-theta                                                                             d                                                               ______________________________________                                                9.37  9.429                                                             18.37 4.824                                                                   28.01 3.183                                                                   28.78 3.099                                                                   35.05 2.558                                                                   37.87 2.373                                                                 ______________________________________                                    

or wherein the base metal component present comprises tin ions and thecomposition displays an X-ray diffractogram comprising the followingdiffraction lines:

    ______________________________________                                                2-theta                                                                             d                                                               ______________________________________                                                12.79 6.915                                                             13.04 6.784                                                                   19.09 4.645                                                                   20.21 4.389                                                                   23.01 3.861                                                                   23.90 3.720                                                                   26.18 3.400                                                                   30.33 2.944                                                                 ______________________________________                                    


9. A catalyst composition containing a noble metal-free catalystcomponent as claimed in claim 1, further comprising an oxygen transfereras a catalytically active component.
 10. A catalyst composition asclaimed in claim 9 wherein the oxygen transferer is selected from amongorganometallic compounds, zeolites, zeolite analogs, aluminophosphatesor meso-porous metal oxides which each comprise at least one metalselected from among Ti, V, Mo, W, Re and Ru.
 11. A catalyst compositionas claimed in claim 10 wherein the oxygen transferer is a titanium orvanadium silicate having a pentasil structure.
 12. A catalystcomposition as claimed in claim 1 on a solid, inert support.
 13. Acatalyst composition comprising:i) a salt of at least one base metal (M)selected from the group consisting of the elements having atomic numbers21-32, 39-42, 48-51, 57-75, and 81-83; ii) phosphate ions (P); and iii)at least one nitrogen source (N);wherein said base metal (M), phosphate(P) and nitrogen (N) are present in the noble metal-free catalystcomposition in a molar ratio of M:P:N=1:0.9-1.3:0.9-1.7.